Abstract
This study was compared and characterized two different alkali (potassium carbonate (PC) and potassium acetate (PA))-catalyzed acetylations of slicewood with vinyl acetate (VA) by a vapor phase reaction. The results revealed that the esterification reaction between VA and the hydroxyl groups of slicewood could be improved by using PC or PA as a catalyst. Additionally, a significant weight percent gain was obtained after VA acetylation with 5% of catalyst. Furthermore, the reactivity of the cellulose hydroxyl groups for VA acetylation was more pronounced at the C2 reactive site compared to acetylation with acetic anhydride. On the other hand, the apparent activation energy of thermal decomposition between 10% and 70% conversion is 174–183, 194–200, and 183–186 kJ/mol for unmodified slicewood and VA-acetylated slicewood with PC and PA, respectively. Accordingly, the thermal stability of the slicewood could be effectively enhanced by VA acetylation, especially for using the PC as a catalyst.
Highlights
In recent years, slicewood and veneer have become a more important part of the wood market because the gradual disappearance of global forest resources has let the supply of large trees to diminish [1]
The results clearly revealed that the change in weight percent gain (WPG) of the vinyl acetate (VA)-acetylated slicewood at 78 ◦ C was not significant
acetic anhydride (AA)-acetylated slicewood (WPG 18%) (B); and VA-acetylated slicewood with potassium carbonate (PC) (C) and Alkali-catalyzed acetylation with VA by vapor phase reaction could be used as an alternative process for wood acetylation, and in which the optimal catalyst loading was 5%
Summary
Slicewood and veneer have become a more important part of the wood market because the gradual disappearance of global forest resources has let the supply of large trees to diminish [1]. Several physical and chemical methods, such as acetylation, heat treatment, and sol-gel treatment, have been used to improve the properties and durability of wood [2,3,4,5]. Among these known approaches, acetylation with acetic anhydride (AA) is one of the best chemical modifications, with corresponding products having already been commercialized in the USA, Europe, and Japan [6,7,8,9]. Using AA as a reactant has a main drawback of generating acetic acid as a by-product during the reaction, which results in undesirable odors and is difficult to remove from wood after acetylation due to its high boiling point (ca. 78 ◦ C) [3,6,7,11,12]
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